Device for stirring molten metal

ABSTRACT

A device, similar to a stopper-rod and stopper head assembly, for immersion in molten metal to provide gaseous agitation thereof.

United States Patent [5 6] References Cited UNITED STATES PATENTS [72]Inventor Daniel E. Moniot Pittsburgh, Pa.

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266/34 F27d 3/ 16, C216 5/34 ABSTRACT: A device, similar to astopper-rod and stopper 266/34, 34 head assembly, for immersion inmolten metal to provide gase- (PP), 34 (T), 34.1, 34.2, 34 (V) ousagitation thereof.

[50] Field PATENTEOFEB23|9H I 3565412 6.45 SOURCE INVENTOR.

DEVICE FOR STIRRING MOLTEN METAL There have been many attempts to injectgas into masses of molten metal in such as holding ladles, tundishes andthe like. This has been accomplished by many different devices in thepast. One such method, a lance, having temporary resistance to moltenmetal and slag was rapidly thrust into the top surface of the metal toquickly inject the gas and then removed. Another method has beenconstructing a large part of a wall of a vessel of a porous material orthe use of a tuyere construction. It'has also been accomplished bypermanently attaching a porous plug in an aperture in the base of avessel.

The method having the most contemporary prominence is the one using aporous plug. However, this has the disadvantage that the vessel has tobe modified extensively to attach the plug, and, attachment anddetachment is difficult since the plug is part of a more or lesspermanent structure on the vessel. In addition, it has been found thatwhen gas is passed through a porous plug into a ladle, a portion of thegas passes through the porous plug sidewalls and into the refractorylin-' ing the ladle bottom. This has caused a great deal of distress tosteel producers.

Accordingly, an object of the present invention is to provide a gasinjecting device which is inert toand impervious to molten metals andwhich has pores therein through which gases will pass, which is not apart of the molten metal containing vessel, which will not tendto spalldue to thermal shock upon introduction into the molten metal and whichwill not react with the slag formed during treatment of the moltenmetal.

Another object of the invention is to provide for the stirring of amolten metal mass with an apparatus that is simpler and less expensiveto operate than existing devices, such as, rotating furnaces,electromagnetic stirring, porous plugs for insertion into ladle bottoms,while achieving comparable or even better efficiency. 1

Other objects of the invention will, in part, become apparenthereinafter.

Briefly, the device of the invention consists of an elongated tubularconduit for conveying a gas, such as, argon or helium. A gas source isattached to the upper endof the conduit and gas insufflating head isattached to the bottom end of the conduit. The head consists of anouter, cylindrical, gas impermeable, refractory shell. Within the shellis disposed a porous refractory plug which is in communication with thetubular conduit to receive the gas. i

The invention has thus been generallydescribed and now will be referredto in more detail byreference to the accompanying drawings, the singleFIG. of which is an elevation view, partly in section, of an immersiondevice according to the invention.

Referring to the drawing, there ,is' shown the immersion device 10. Thenumeral 12 designates the tubular conduit which is generally composed ofa metal, such as, steel. Attached to the upper end of the conduit is agas source which supplies the required gaseous material to the conduitby means of a hose 13, or the like. The gas source may be attached tothe conduit by any means known to those skilled in the art. The drawingshows the connecting means as being a cap 14 fitting over a projectinglug 15 at the top of the conduit. The lower end of the conduit isflanged so as to support protective refractory sleeves 16. Theirnecessity is quite obvious. In order to properly stir and remove thedesired impurities from the molten metal, the device must be immersedtherein for the required period of time. The metal conduit would meltunder these conditions. The use of a conduit composed of a refractoryhas been considered; however, such conduits are quite difficult tomanufacture and are not economical. The sleeves are composed of a heatresistant material, such as, fireclay or high alumina and this serves toadequately protect the conduit from contact with molten metal for aslong as necessary.

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The gas insufllating head 18 is attached to the lower flanged end of thetubular conduit. The head. contains a relatively small, centrallydisposed aperture 20 coaxially aligned with the aperture 22 in thetubular conduit. The aperture 20 o ens into a larger aperture 24 towardthe lower end of the s ell.

Communication between the two apertures is defined by upper flat surface26. The shell is connected .to the conduit by means of a pipe 28 havinga lower, outer peripheral flange 30. The pipe passes through the smallaperture 20 and is secured to the conduit by means, such as, a threadedportion 32. Of course, other means known to those skilled in the art forsecuring the pipe to the conduit are readily available. The flange 30 onthe pipe is disposed in contact with the surface 26 joining the smallaperture 20 to the larger aperture 24. This in effect brings therefractory shell into close abutment with the flange 30 of tubularconduit 12 and secures it thereto. The porous plug 34 is disposed in thelarger aperture with one end being in contact with the flanged pipe, thesidewalls being in contact with the walls of the larger aperture and theother end being free to allow the gaseous material to pass therefrom.

The device of the invention may be fabricated in a variety of ways;however, it is preferred to construct it in the following manner: Therefractory shell is formed by vibration coasting a refractory batch in amold conforming to the contours of the shell. The shell is preferablycomposed of a high alumina refractory material analyzing at least aboutpercent A1, 0 on an oxide basis. The refractory grains are bonded withfrom about 2 to 15 percent P 0 provided by orthophosphoric acid. Afterthe shell has been cured by drying, the flanged pipe is passed upthrough the relatively small aperture so that the flange 30 is inabutment with the surface 26. After the flanged pipe is in place, theshell and flanged pipe act as a mold for the porous plug. The porousplug thus is formed in situ by casting a refractory batch in the largeraperture; Preferably, the batch is composed of calcined South Americanbauxite with about 2 percent by weight, of bentonite. The batchsimilarly is bonded with P 0 in amounts of up to 15' percent. Aftercomplete fabrication, the assembly is then dried at a temperature ofabout 500 F. The grind of the batch for the refractory porous plug issuch that after drying, the plug will have a porosity of about 25percent. After curing by drying, the threaded end of the flanged pipe isthen secured to the threaded female socket of the tubular conduit untilthe shell fits securely against the conduit.

In operation, after the vessel, such as a steel ladle, is filled withmolten metal, the stirring device is immersed therein. The gas supply isthen activated and gas is fed through the hose to the tubular conduit.The gas passes through the conduit and then through the pipe anddiffused down through the porous plug and into the molten metal in smallbubbles which rise up through the molten mass to carry out the desiredmetallurgical effect.

I claim:

1. A device for immersion in molten metal to provide gaseous agitationthereof consisting of an elongated tubular conduit for conveying agaseous substance, a gas source attached to one end and a gasinsufflating head attached to the other end, the head consisting of aouter, cylindrical gas impermeable refractory shell, said shellcontaining a relatively small, centrally disposed aperture coaxiallyaligned with the aperture in the tubular conduit, which aperture opensinto a larger aperture toward the lower end of the shell, the shellbeing connected to the conduit by means of a pipe having a lower outerperipheral flange, said pipe passing through the small aperture andbeing secured to the conduit, the flange being in contact with thesurface joining the small aperture to the larger aperture and an inner,porous refractory plug disposed in the larger aperture adjacent theperipheral flange.

2. The device of claim 1 in which the tubular conduit containsrefractory material on the outer surfaces thereof.

1. A device for immersion in molten metal to provide gaseous agitationthereof consisting of an elongated tubular conduit for conveyiNg agaseous substance, a gas source attached to one end and a gasinsufflating head attached to the other end, the head consisting of aouter, cylindrical gas impermeable refractory shell, said shellcontaining a relatively small, centrally disposed aperture coaxiallyaligned with the aperture in the tubular conduit, which aperture opensinto a larger aperture toward the lower end of the shell, the shellbeing connected to the conduit by means of a pipe having a lower outerperipheral flange, said pipe passing through the small aperture andbeing secured to the conduit, the flange being in contact with thesurface joining the small aperture to the larger aperture and an inner,porous refractory plug disposed in the larger aperture adjacent theperipheral flange.
 2. The device of claim 1 in which the tubular conduitcontains refractory material on the outer surfaces thereof.